Attempt to determine whether therapy with an extract of heparanized C5-positive plasma is useful in the treatment of spontaneous leukemia in mice. In some studies, plasma therapy will be used in combination with tumor necrosis factor, endotoxin, and cytoxan. Efforts will be undertaken to determine the effect of plasma therapy on levels of complement components with Clq reactants in both preleukemic and leukemic mice. Any modification of the study design must have the prior approval of the Project Officer before being instituted.